esmithga

Hello Fellow modelers.

I just purchased a new old stock Saito 80T off eBay and while adjusting, oiling and cleaning the engine I broke a rocker arm.

I cannot find any on the internet and I currently have a call into Horizon Hobby to see what they suggest but so far no call back.

Attached are some photos of the rocker.

The length is about 28 to 29 mm and width at the widest part is 5 mm.

If anyone has any idea what I can use or if anyone has a used rocker that you are willing to part with PM me.

I found this one on the internet and it appears to be about the same but missing the set screw use to secure the rocker to the rocker pin.

I broke the current one by over tightening the rocker set screw.

http://www.gravesrc.com/saito-rocker-arm.html

I need new rocker cover gaskets too but if I can't find any I'll will cut some out of some gasket material.

Any ideas?

Thank you,

cahusker

My Feedback: (50)

Since the 80 and 90 twins use the cylinders from the 40 and 45 singles the parts are interchangeable. So you need SAI5041 rocker arm, SAI5042 rocker arm adjusting nuts and SAI5032B gasket kit for the rocker arm cover gaskets (plus others). All are available from Horizon and others. Just type these part numbers into the search line on the Horizon site and place your order, they usually ship the same day if ordered early in the day.

esmithga

Thank you.

esmithga

OK Still have the problem. I ordered the rocker arms and the match except for the set screw. The old 80T used a set screw in the rocker to hold it to the shaft.
The new ones match except for the set screw.

So smart me thought - I can just drill it out and tap it. It is a 3mm - 50 so I purchased a tap and drill that matches the tap. I did not know these were made out of very hard metal. I went through about 6 drill bits before I got the hole drilled. Now to tap it. The metal is so hard that the tap will not even start.

Any idea what else I could do?

spaceworm

Why is it that the new rocker arms do not need the setscrew? Are they located by spacers or something that obviates the setscrew? Take a look at the exploded view of the new 80T for how it is done. Or, as has been said, look at the 40 and 45 singles exploded views. Just what I would do. Good luck
Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180

esmithga

Hi,

Attached are some pictures of the new rocker and old cracked rocker. As you can see the rocker NEEDS a set screw to hold the rocker and the rocker pin in place.

This is an old design since the new Saito rocker pins are threaded on one end and thread into the rocker holder.

You can see in the attached pictures the new untouched rocker and the old broken rocker along with the rocker pin and a separate picture of the engine.

The new and old rockers match except for the missing set screw hole in the new rocker.

Does anyone have a better idea of how to fix this issue? I need a rocker arm that has a set screw to hold the rocker pin in place.

As I said above. I tried to drill one of the new rockers (2 came in the package) and tried to tap it to match the 3mm set screw but the metal is so hard that I broke 6 drill bits and the tap will not even start to cut the threads.



Thank you for your valued input.

spaceworm

Ok, pictures helped. How about drilling and tapping vertically down into the aluminum rocker pin supports, maybe on both sides for added security, so the tapped holes intersect with the rocker pin bearing holes. Use setscrews on each side tightened down on the rocker pin. Maybe even grind small flats on the rocker pin for the setscrews to bite against, Use Loctite on the setscrew or use the ones with a nylon pellet on the threaded part to lock into the internal thread. Drilling and tapping the aluminum head material should be lots easier than dong so into the rocker itself. Good luck.

Sincerely, Richard

Well, I thought some more about what I said and decided that I would not want to drill holes in the head of any Saito. So, here is another idea. Since the rocker cover fits over the rocker pin holes in the supports, just put the pin and rocker in place and put the cover on securely.

spaceworm

[QUOTE=spaceworm;12006506]Ok, pictures helped. How about drilling and tapping vertically down into the aluminum rocker pin supports, maybe on both sides for added security, so the tapped holes intersect with the rocker pin bearing holes. Use setscrews on each side tightened down on the rocker pin. Maybe even grind small flats on the rocker pin for the setscrews to bite against, Use Loctite on the setscrew or use the ones with a nylon pellet on the threaded part to lock into the internal thread. Drilling and tapping the aluminum head material should be lots easier than dong so into the rocker itself. Good luck.

Sincerely, Richard.[/QUOTE

Well, I thought some more about what I said and decided that I would not want to drill holes in the head of any Saito. So, here is another idea. Since the rocker cover fits over the rocker pin holes in the supports, just put the pin and rocker in place and put the cover on securely.

cahusker

My Feedback: (50)

Sorry I missed the fact that the rocker arm had a set screw in it. Your engine is the early or original design so not too likely there are any parts available from Horizon for it. Don't know if there is any chance in contacting Saito factory directly to see if anything is available. Mean while spaceworm's suggestions are good and the second one doesn't require any modification if the valve cover fits tight enough to keep the shaft in the towers or with a small shim possibly. Need advise from a machinist on how to get a tapped hole in one of the new ones if it is even possible, but poses the question on how it was done originally.

esmithga

Thanks for all your comments and suggestions.

I got really smart today. I contacted BJs Engines to see if he had any parts engines and he had 2 rockers. I need one. Price was cheaper than the drill bits I broke and the metric tap set I bought.

He did some warranty work on an RCV 90 SP for me years ago and did a very nice job.

spaceworm

Very glad you got to fix it right.

Sincerely, Richard

cahusker

My Feedback: (50)

Good information about BJs Engine Service, I will keep that in mind on some of the tough ones I work on from time to time as well as a solution for others.

esmithga

OK - It's been months since I broke the rocker arm. I was not able to get a good replacement until now. What a ride. The rocker I got from BJs and ordered from Horizon were a match except for they both were missing the set screw hole. I tried to drill one of the rockers and broke about 6 drill bits getting through and then I could not tap the hole for the set screw as the tap would not cut the metal. I am not sure what these are made of but they are very hard. I thought about finding a machine shop that would have the proper tools to drill and tap the rocker but decided that was an endless search. Soooo I reached out to Horizon again and they sent me to http://www.macgregor.co.uk/ in the UK. They were one of the original suppliers of Saito I guess before Horizon. They contacted Saito in Japan and Saito had three sets left in stock. MacGregor ordered one set for me and the pair came last Tuesday. So finally I have my engine back together and running. I also bought a second 80T off ebay so now I have two running twin 80 Ts.

The one concern I have is these are both the single carb versions. At low (idle) RPM one cylinder cuts out from time to time so I am thinking about trying a CDI ignition module on one of them. They both run very smooth at all RPMs and when one cylinder cuts out it keeps running on one cylinder and a few times it must have gotten hot enough inside to restart at mid RPM.

Will see how it goes.

Hemikiller

My Feedback: (125)

I have the 80T as well. Glad you were able to get your parts, it's a neat engine with a unique sound due to the firing order. The rocker arm is most likely heat treated after machining, which is why you had such trouble drilling it. You would really need to anneal the arm, perform your machining and re-heat treat. The set screw is necessary as the rocker arm shaft rotates in the stands, not the current method of the arm pivoting on the shaft.

Saito offered a dual-carb update kit for the 80T, I picked one up several years ago for mine. Keep an eye on eBay or the RC forums, they turn up from time to time.